The Titanic exhibit, now at the South Florida Science Museum in West Palm Beach, is only the tip of the iceberg when it comes to undersea treasures.

Dozens of sunken Spanish galleons remain undiscovered off Florida's coast, many hidden by centuries of shifting sands, yet holding tons of gold and silver worth tens of millions of dollars.

"There are probably 30 to 40 old Spanish ships, from the 1500s up to the late 1600s, that are sunk around Florida," said Terry Armstrong, a Merritt Island treasure hunter who has written two books on historic shipwrecks. "There's a lot of money lying around on the sea bottom."

Hundreds more undiscovered shipwrecks from various eras, including pirate ships, slave ships, Civil War ships and early 1900s cargo haulers, are scattered around the state, including the deep waters off South Florida. Additionally, ancient Indian canoes are buried beneath the silt of many inland lakes and waterways, authorities said.

They may not be laden with riches but are historically valuable nonetheless, said Corey Malcom, director of archaeology for the Mel Fisher Maritime Museum in Key West.

"There's a heck of a lot history still on sea floor," he said.

The non-profit Mel Fisher Maritime Heritage Society, for example, currently is trying to find the Guerrero, a Cuban pirate ship transporting 561 slaves to Havana when it sank near Key Largo in 1827.

Still, Spanish galleons remain every treasure hunter's dream, as most were loaded with coins, ingots and objects made of gold and silver.

Powered by the wind, often weighing more than 1,000 tons, the ships were dispatched in fleets to the New World in the 16th and 17th centuries. They would pick up opulent items from around the Caribbean, Central and South America, then group together in Havana before returning to Spain in convoy fashion.

Along the way, they would pass by Florida and occasionally get attacked by pirates, torn apart by hurricanes or caught on shoreline rocks and shoals.

"By the time the Spanish sailors would get all the ships together, it always seemed to be in the summer and the middle of hurricane season," Armstrong said.

In 1733, a hurricane struck a Spanish galleon fleet off Marathon in the Keys. One of the ships, the San Jose, was carrying almost 7 million pesos in gold when it sank. Buried in sand under 30 feet of water, the wreck site today is a state historic preserve.

Although most of the ships returned safely to Spain, making it the richest country in the world, the relatively small percentage that foundered offered enormous wealth to whoever found them.

That is, until President Ronald Reagan signed the Abandoned Shipwreck Act in 1988, making any historic finds the property of respective states.

"It's public property, and you can't steal it," said Roger Smith, state underwater archeologist with the Florida Bureau of Archaeological Research.

Smith said treasure hunters need to apply for a "permit to explore historic shipwrecks," and the chances of being granted permission to excavate a ship and recovering its bounty are remote. Because shipwrecks are valuable pieces of history, the state would prefer they remain undisturbed, no matter how much they hold in riches.

"The idea of keeping what you find is a 19th and early 20th Century notion, whose time has come and gone," Smith said.

On the other hand, treasure hunter Mel Fisher won a battle in the U.S. Supreme Court to recover 40 tons of gold and silver from the Spanish galleon Nuestra Senora de Atocha, which sank near the Dry Tortugas in 1622 – and which Fisher discovered in 1985. As part of the agreement, Fisher donated 20 percent of the bounty to the state.

Currently, no companies are seeking permits to explore historic shipwrecks, Smith said. But he added that weekend boaters frequently spot something odd on their fish-finders and report it to the state, resulting in some ancient Indian canoes being found.

The Bureau of Archaeological Research encourages divers to check out known historic wrecks. Among the most popular is the Copenhagen, a steel-hulled steamship that attempted to transport 4,940 tons of coal from Philadelphia to Havana but ran aground about three-quarters of a mile offshore from Lauderdale-By-The-Sea in 1900. Today it's an artificial reef.

Despite the hidden wealth around Florida, the Titanic remains the most revered shipwreck in history because of its tragic ending, with more than 1,500 perishing after the ocean liner hit an iceberg in the North Atlantic in April 1912. Robert Ballard, an oceanography professor at the University of Rhode Island, found the wreck two and a half miles below the surface, using submersibles, in 1985.

About 100 of the items found in the Titanic's debris field are on display at the science museum through April 20. Among them are cracked perfume vials, chipped china plates and bent chandeliers.

"You couldn't say the Titanic was a treasure ship, like those that sank off the coast of Florida," said Lewis Crampton, museum president and CEO. "But some of these artifacts have incalculable personal resonance with people."